Silicone adhesive for semiconductor element

Abstract

A silicone adhesive for a semiconductor element that is suitable as a die bonding material for fixing a light emitting diode chip to a substrate. The adhesive includes (a) an addition reaction-curable silicone resin composition having a viscosity at 25° C. of not more than 100 Pa·s, and yielding a cured product upon heating at 150° C. for 3 hours that has a type D hardness prescribed in JIS K6253 of at least 30, (b) a white pigment powder having an average particle size of less than 1 μm, and (c) a white or colorless and transparent powder having an average particle size of at least 1 μm but less than 10 μm. The adhesive exhibits high levels of concealment, effectively reflects light emitted from the LED chip, and also exhibits favorable chip positioning properties, superior adhesive strength, and excellent durability.

What is claimed is: 
     
       1. A light emitting device comprising a gold-plated substrate, a light emitting element and a cured resin layer interposed between the gold-plated substrate and the light emitting element, wherein said cured resin layer comprises a cured product of a silicone adhesive comprising components (a), (b), and (c):
 (a) an addition reaction-curable silicone resin composition, having a viscosity at 25° C. of not more than 100 Pa·s, and yielding a cured product upon heating at 150° C. for 3 hours that has a type D hardness prescribed in JIS K6253 of at least 30, 
 (b) a white pigment powder having an average particle size of less than 1 μm and 
 (c) a white or colorless and transparent powder having an average particle size of at least 1 μm but less than 10 μm wherein 
 a combination of components (b) and (c) is present in an amount of 12 to 600 parts by mass per 100 parts by mass of component (a). 
 
     
     
       2. The light emitting device according to  claim 1 , wherein said cured resin layer comprises a cured product of a white silicone adhesive comprising components (a), (b) and (c):
 (a) an addition reaction-curable silicone resin composition, having a viscosity at 25° C. of not more than 100 Pa·s, and yielding a cured product upon heating at 150° C. for 3 hours that has a type D hardness prescribed in JIS K6253 of at least 30, 
 (b) a titanium oxide powder having an average particle size of less than 1 μm, and 
 (c) at least one powder selected from the group consisting of an alumina powder and a crystalline silica powder and having an average particle size of at least 1 μm but less than 10 μm, wherein 
 a combination of components (b) and (c) is present in an amount of 12 to 600 parts by mass per 100 parts by mass of component (a), and 
 the blend mass ratio of component (b) to component (c) is within a range from 0.1 to 20, 
 wherein component (a) comprises components (A), (B), (C) and (D): 
 (A) a linear organopolysiloxane having at least two alkenyl groups bonded to silicon atoms within each molecule, and having a viscosity at 25° C. of not more than 1,000 mPa·s, 
 (B) a polyorganosiloxane represented by an average composition formula (1):
   (R 1 R 2   2 SiO 1/2 ) m (R 1 R 2 SiO 2/2 ) n (R 2   2 SiO 2/2 ) p (R 1 SiO 3/2 ) q (SiR 2 (OR 3 )SiO 2/2 ) r (SiO 4/2 ) s    (1)
 
 
 wherein R 1  represents an alkenyl group or a monovalent hydrocarbon group other than an alkenyl group; R 2  represents a monovalent hydrocarbon group that does not contain an alkenyl group, provided that at least 80% of R 2  groups are methyl groups; R 3  represents a hydrogen atom or an alkyl group; m, n, p, q, r and s are numbers that satisfy m≧0, n≧0, p≧0, q≧0, r≧0 and s≧0 respectively, provided that m+n>0, q+r+s>0, and m+n+p+q+r=1, 
 which at 25° C. is either a liquid having a viscosity of at least 1,000 Pa·s or a solid, in an amount that provides 60 to 90 parts by mass of component (B) per 100 parts by mass of a combination of component (A) and component (B), 
 (C) an organohydrogenpolysiloxane represented by an average composition formula (2):
   R 4   a H b SiO (4−a−b)/2    (2)
 
 
 wherein R 4  represents a monovalent hydrocarbon group other than an alkenyl group, and at least 50% of R 4  groups are methyl groups; and a and b are positive numbers that satisfy 0.7≦a≦2.1, 0.001≦b≦1.0 and 0.8≦a+b≦3.0, 
 having at least two SiH bonds within each molecule, and having a viscosity at 25° C. of not more than 1,000 mPa·s, in an amount that yields a total number of SiH bonds that is 0.5 to 5.0 times a total number of alkenyl groups within a combination of component (A) and component (B), and 
 (D) an effective amount of a platinum group metal-based catalyst, and wherein the white silicone adhesive is present in cured state on the light emitting device that comprise gold electrode. 
 
     
     
       3. The light emitting device according to  claim 1 , wherein component (c) comprises alumina. 
     
     
       4. The light emitting device according to  claim 3 , wherein component (c) is an alumina powder composed of alumina particles with a shape of flake. 
     
     
       5. The light emitting device according to  claim 2 , wherein the organopolysiloxane of component (A) is a linear organopolysiloxane having at least two alkenyl groups bonded to silicon atoms within each molecule, in which a main chain comprises repeating diorganosiloxane units, and both molecular chain terminals are blocked with triorganosiloxy groups. 
     
     
       6. The light emitting device according to  claim 2 , wherein an amount of alkenyl groups is within a range from 0.01 to 1 mol/100 g relative to a solid fraction of component (B). 
     
     
       7. The light emitting device according to  claim 2 , wherein an amount of component (B) is within a range from 70 to 80 parts by mass relative to 100 parts by mass of a combination of component (A) and component (B). 
     
     
       8. The light emitting device according to  claim 1 , wherein the blend mass ratio of component (b) to component (c) is within a range from 0.2 to 10. 
     
     
       9. The light emitting device according to  claim 1 , wherein the blend mass ratio of component (b) to component (c) is within a range from 0.5 to 5. 
     
     
       10. The light emitting device according to  claim 1 , wherein a combination of components (b) and (c) is present in an amount of 25 to 350 parts by mass per 100 parts by mass of component (a). 
     
     
       11. The light emitting device according to  claim 1 , wherein a combination of components (b) and (c) is present in an amount of 40 to 350 parts by mass per 100 parts by mass of component (a). 
     
     
       12. The light emitting device according to  claim 1 , wherein a blend amount of component (c) is from 2 to 400 parts by mass, per 100 parts by mass of component (a). 
     
     
       13. The light emitting device according to  claim 1 , wherein a blend amount of component (c) is from 5 to 200 parts by mass, per 100 parts by mass of component (a). 
     
     
       14. The light emitting device according to  claim 2 , wherein component (D) comprises at least one member selected from the group consisting of platinum black; rhodium palladium; a platinum chloride; a chloroplatinic acid; a chloroplatinate; an alcohol-modified chloroplatinic acid; a complex of chloroplatinic acid and an olefin; platinum black supported on alumina, silica or carbon; palladium supported on alumina, silica or carbon; a rhodium-olefin complex; chlorotris(triphenylphosphine)rhodium; and a complexes of platinum chloride, chloroplatinic acid or a chloroplatinate with a vinyl group-containing siloxane. 
     
     
       15. The light emitting device according to  claim 2 , wherein component (D) comprises a silicone-modified chloroplatinic acid. 
     
     
       16. The light emitting device according to  claim 2 , wherein component (D) comprises chloroplatinic acid modified with tetramethylvinyldisiloxane. 
     
     
       17. The light emitting device according to  claim 2 , wherein component (A) comprises at least one member selected from the group consisting of 
       
         
           
           
               
               
           
         
       
     
     
       18. The light emitting device according to  claim 2 , wherein component (C) is present in an amount that yields a total number of SiH bonds that is 0.7 to 3.0 times a total number of alkenyl groups within a combination of component (A) and component (B). 
     
     
       19. The light emitting device according to  claim 2 , wherein the organohydrogenpolysiloxane of component (C) comprises 4 to approximately 50 SiH groups within each molecule that are positioned either at the molecular chain terminals or at non-terminal positions within the molecular chain or are positioned at the molecular chain terminals and at non-terminal positions within the molecular chain. 
     
     
       20. The light emitting device according to  claim 2 , wherein component (C) comprises at least one member selected from the group consisting of 1,1,3,3-tetramethyldisiloxane; 1,3,5,7-tetramethylcyclotetrasiloxane; tris(hydrogendimethylsiloxy)methylsilane; tris(hydrogendimethylsiloxy)phenylsilane; methylhydrogencyclopolysiloxane; a cyclic copolymer of methylhydrogensiloxane and dimethylsiloxane; a methylhydrogenpolysiloxane with both molecular chain terminals blocked with trimethylsiloxy groups; a copolymer of dimethylsiloxane and methylhydrogensiloxane with both terminals blocked with trimethylsiloxy groups; a dimethylpolysiloxane with both terminals blocked with dimethylhydrogensiloxy groups; a methylhydrogenpolysiloxane with both terminals blocked with dimethylhydrogensiloxy groups; a copolymer of dimethylsiloxane and methylhydrogensiloxane with both terminals blocked with dimethylhydrogensiloxy groups; a copolymer of methylhydrogensiloxane and diphenylsiloxane with both terminals blocked with trimethylsiloxy groups; a copolymer of methylhydrogensiloxane; a diphenylsiloxane and dimethylsiloxane with both terminals blocked with trimethylsiloxy groups; a copolymer of methylhydrogensiloxane, methylphenylsiloxane and dimethylsiloxane with both terminals blocked with trimethylsiloxy groups; a copolymer of methylhydrogensiloxane, dimethylsiloxane, and diphenylsiloxane with both terminals blocked with dimethylhydrogensiloxy groups; a copolymer of methylhydrogensiloxane, dimethylsiloxane and methylphenylsiloxane with both terminals blocked with dimethylhydrogensiloxy groups; a copolymer comprising (CH 3 ) 2 HSiO 1/2  units, (CH 3 ) 3 SiO 1/2  units and SiO 4/2  units, a copolymer comprising (CH 3 ) 2 HSiO 1/2  units and SiO 4/2  units, and a copolymers comprising (CH 3 ) 2 HSiO 1/2  units, SiO 4/2  units and (C 6 H 5 ) 3 SiO 1/2  units.